Time and time again, Martin has reiterated that he writes and edits at his own pace, as well that projected deadlines are never exact. Still, after years of speculation, Martin at least put forth in (where else) a LiveJournal comment that The Winds of Winter would likely be published within 2017 (before immediately hedging that bet):

Not done yet, but I’ve made progress. But not as much as I hoped a year ago, when I thought to be done by now.

I think it will be out this year. (But hey, I thought the same thing last year).